Smart membranes today have a very limited range of performance. Membranes exist that can switch hydrophobicity based on pH or temperature signals, and conducting polymer membranes that can swell and shrink as they are charged and discharged, to modulate pore size. For example, smart membranes have largely consisted of membranes containing a thermally responsive polymer such as PNIPAM; pH-responsive polymers based on carboxylates or amines; or both simultaneously. The active component of these membranes is covalently grafted to the base membrane using methods that are not extendable to a wide variety of functionalities.
That is, while technologies exist that enable a membrane surface to be modified, they are very challenging and inefficient. A goal for ‘smart membrane’ technology is to offer a wide range of membrane functionality to suit an individual application, but today such customization can be expensive.